I do a lot of big blowups and would like to do even bigger. I find there seems to be no all-in-one cause for noise. At 1600 I've gotten some fairly clean files, then at 200 too much noise. There seems to be no consistent rule about how to avoid noise, although light, ISO and sensor design (lens design?) I believe are primary contributors. I work with the XT -- no, I'm happy with it -- but I would like to hear from someone who has used both smaller and full frame sensors and their take on noise. Anyone work with the Nikon D3?
Ninja warrior only when really needed.
sam ward wrote:
There seems to be no consistent rule about how to avoid noise, although light, ISO and sensor design (lens design?) I believe are primary contributors.
Actually, the one major contributor to noise (or lack of) is proper exposure.
The more you need to monkey with the exposure after the fact the more noise you're bound to find in a particular shot.
Yup, shoot RAW, and expose to the right (on your histogram) for the best noise control. On my old XT I used to overexpose by 1/3 of a stop in almost all circumstances, and got much improved results.
Don't you guys find that pulling down a right-exposed image introduces banding into skies and other large areas of gradation? This is one reason why I'm looking forward to 14-bit.
Proper exposure is key. Also, I frankly don't care about the noise that's generated by all the current DSLRs nowadays...they're clean enough to look great at any print size. Sure, noise may be visible, but as long as the chroma noise is gone, it'll just look like film grain, or darn close. Heck, today's ISO 3200 shots look cleaner than ISO 800 did on film, so it's hard to complain.
sam ward wrote:
At 1600 I've gotten some fairly clean files, then at 200 too much noise.
This kind of answers your question. If your exposure is wrong then ISO 50 or ISO a million won't keep the noise down after you tweak the curves to get the exposure back right.
Plus, it also depends on the dynamic range of the scene. If you have super bright parts and really dark shadows there is that much the camera can do. If you expose to the right for the highlights, the shadows will be way underexposed and noisy, but at least the rest of the image will be ok.
panos.v wrote:
This kind of answers your question. If your exposure is wrong then ISO 50 or ISO a million won't keep the noise down after you tweak the curves to get the exposure back right.
Plus, it also depends on the dynamic range of the scene. If you have super bright parts and really dark shadows there is that much the camera can do. If you expose to the right for the highlights, the shadows will be way underexposed and noisy, but at least the rest of the image will be ok.
I have also found that exposing to the right by 1/3 makes a significant difference in noise reduction right out of the camera. I have not noticed any banding due to this practice. What I have noticed is a better final result at ISO 3200.
I used to expose to the right all the time with my 1D, which really needed it. The 20D benefits from this as well.
With the 5D, I don't bother. If anything, I underexpose slightly to preserve highlights. The overall lack of noise from the 5D sensor, combined with Sean Puckett's "Shady" plugin for Bibble, allows me to pull several stops (if necessary) from my RAW files with minimal noise.
If you are shooting jpegs and expose to the right then you may easily burn out some highlights in one or more colours before there is any sign of it on the LCD histogram or blinkies. e.g. you can easily turn blue sky into grey sky without getting a warning.
Shooting in raw mode maximises the effective dynamic range and allows you more scope to increase exposure without causing damage.
Of course exposing to the right is only part of the story. It allows you to increase the ratio of signal to noise seen by the sensor and so disguise the level of noise. It doesn't reduce the noise - it just buries it in good subject data. The other part is rarely mentioned but requires that you underexpose the image in the processing or raw conversion to undo the overexposure that you introduced. Otherwise you'll have an overexposed image. When you darken the image in processing you will also darken the noise so that it will be less obvious than if you just shot normally in the first place. The noise was introduced to the image data before it got stored in the image file. The more you can do to bury it in good image data at the time of capture the better, but a noisy image may be better than an image with burned out highlights.
Also, noise is most evident in areas of low signal to noise ratio. This includes shadows and dark objects even if they are photographed on a bright day or in good light with a correct exposure or some degree of overexposure.
I recommend that you invest in a good dedicated noise reduction program such as Neat Image Pro or Noise Ninja. They can do wonders to an image without throwing away the subject data that is buried in the noise.
